Yes, under the assumption that all lives involved are equal. The decision to not kill the one person is the same decision that leads to the death of a thousand. Doing nothing doesn't relieve you of moral responsibility. It is a decision just like doing something is.

it is not epistemologically possible to know that killing 1 person now will directly save 1000 in the future outside of a contrived hypothetical scenario where we are assumed to have perfect knowledge. If implemented as policy it could promote ignorance of unintended consequences and greater death.

There is no built in value for life, morality is something one comes up to protect oneself. Accordingly to reasons, situation and outcome, killing anyone to either save or not save is completely justifiable.